STRAIN-GRADIENT STRESS-ANALYSIS IN SAINT-VENANT BENDING

Light beam deflections caused by stressor strain gradients are investi gated analytically and experimentally in homogeneous beam specimens wh ich are subjected to a particular case of flexure with shear. This stu dy is a generalization of the prior analytical-experimental examinatio n of strain-gradient light deflections produced in stressed plates, wh ich had concentrated on the simplest case where information of interes t is collected along a line of symmetry of the stress field. Main purp ose of the present investigation is to document the efficacy of the st rain-gradient method in analysis of the general case of stress state. The most interesting stress state is that in a beam subjected to the S aint-Venant bending, where the transversal and the longitudinal axes o f the beam are in pure shear. The obtained results are compared with t he predictions of the developed analytical models and with the predict ions of Filon's stress function. The procedures of evaluating the phot oelastic and material coefficients using strain-gradient techniques we re tested positively.